Axle won't go in far enough

slide a tape measure in there and see where it bottoms on the button. Then you can tell if the axle is the issue. You say 1/4 inch? SG's have 2 splines that must line up! turn your axle when you push it in to engage the inner SG splines inside the carrier splines. perhaps you are hanging up on the inside splines? Or am I thinking of a Dana?